Abstract Heresies

fold-left has this basic recursion: (fold-left f init ()) = init (fold-left f init (a . d)) = (fold-left f (f init a) d) A straightfo...

Here's a 2x2 matrix: [64919121 -159018721] [41869520.5 -102558961] We can multiply it by a 2 element vector like this: (defun mxv (a b...

fold-left takes arguments like this: (fold-left function init list ) and computes * (fold-left (lambda (l r) `(f ,l ,r)) 'init ...

Here is the delta function: δ = (lambda (f) (f f)) . Delta takes a function and tail calls that function on itself. What happens if we...

If you have an expression that is an application, and the operator of the application is a lambda expression, then you can β-reduce the ...

In McCarthy's early papers on Lisp, he notes that he needs a modified version of subst which needs to be aware of quoted expressions (...

You don't need a data structure to make a lookup table. You can make a table just out of the lookup function. In this example, we ...